Nobody who makes a serious movie about ghosts ever depicts his spirits as people wearing bed sheets with eyeholes — that’s a cut-rate Halloween costume, right? But David Lowery does exactly that in the Sundance film “A Ghost Story,” which premiered at Sundance in January. And somehow, this guy in a sheet breaks your heart.

Lowery shot the film in 19 days immediately after finishing his acclaimed big-budget film “Pete’s Dragon,” but “A Ghost Story” is a defiant return to the artful indies that Lowery made before Hollywood came calling, “St. Nick” and “Ain’t Them Bodies Saints.”

Like the latter film, “A Ghost Story,” which was picked up by A24 prior to the festival, stars Casey Affleck and Rooney Mara. Neither of them say much: She’s not talkative, and he’s hidden beneath that sheet for most of the running time.

Shot in the 1:33:1 ratio, which almost reads as square to viewers, this is a languorous art movie that glories in stillness. Lowery’s camera settles in place and stays there; sometimes he comes in tight and stays put, but more often he backs off and frames the action — or, just as often, the lack of action — from a discreet distance.

The film starts with Affleck and Mara as a young couple, identified only as C and M, who are preparing to leave their rented rural home and move to the city. Given the film’s title, and the point in the movie at which it happens, it’s hardly a spoiler to say that C is killed in a car accident; we watch him lying on a gurney in the morgue, covered with a large white sheet, when he sits up and walks out, making no attempt to dislodge the sheet. (Although he does apparently cut the eyeholes, which are there in the next scene.)

C returns to the house and sees M dealing with her grief. At one point, she comes home, looks at a few cards and letters, then cuts and eats a pie that her landlady has left for her. Sitting on the floor, she finishes almost the entire pie before she runs into the bathroom and throws up. C watches without moving, and so does the camera — the entire sequence is filmed in two lengthy, static shots, conveying immense turbulence while exhibiting stillness and quiet.

On paper, a description of that scene — Rooney Mara eats a pie and throws up while Casey Affleck watches through the eyeholes in a sheet — sounds ridiculous and comic. But in that astounding sequence and throughout this lovely, disquieting film, Lowery takes a fundamentally comic premise and makes it sad and touching.

His ghosts are figures of loneliness and longing; they can knock things over and go bump in the night, but they’re fundamentally passive and helpless. C has a wordless (but subtitled) encounter with another ghost in a nearby house (we know it’s a female ghost because her sheet has a little floral pattern) in which the other ghost tells him that she’s waiting for someone to return to the house. “Who?” he asks. “I don’t remember,” she says.

About 40 minutes into “A Ghost Story,” M leaves the house for the last time; it’s hard to measure the time for sure, because if you can surrender to Lowery’s pacing, time feels suspended. It seems as if the movie could stop right there, and exist as a haunting (no pun intended) miniature.

But a new family moves in, C is disturbed, and he waits for answers that may never come. We do get a party scene featuring a marvelous Will Oldham, as he tries to deliver the meaning of life in a five- or 10-minute monologue that probably contains more words than the rest of the movie. His conclusion, which is probably true and probably beside the point: Everything humans do will eventually fade and disappear.

In this final stretch, C hangs out in the house for centuries (literally) and, in a sense, the movie gets a bit like its main character: It doesn’t really know when to quit. But if you’ve bathed in its rhythms that long, it’s not hard to enjoy soaking in them a little longer, as C dwells upon searching for (albeit passively) a way to let go and find peace and acceptance.

He’s accompanied in that search by Daniel Hart’s gorgeously evocative music, which stands out as part of a brilliantly effective sound design.

And no, you never stop noticing that it’s Casey Affleck in a bed sheet with eyeholes, or wondering why we’re emotionally affected by the journey of a guy in a kid’s Halloween costume. That’s the marvel of “A Ghost Story”: it’s a strange, sad, fragile little thing that should make us snicker, but instead it fills the screen with grace and beauty.

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"Brigsby Bear" Kyle Mooney ("SNL") leads an impressive ensemble in what seems to be a millennial take on "The Truman Show." The title refers to a children's TV show made for an audience of one -- a boy named James, whose life changes after the show's abrupt end. Dave McCary directs from a script by Mooney and Kevin Costello. Claire Danes, Mark Hamill, Greg Kinnear and Michaela Watkins co-star.

"The Big Sick" Socially relevant fare that's based on a true story is often a winning combination for Sundance features. "Silicon Valley" star Kumail Nanjiani and girlfriend Emily V. Gordon wrote this true tale of bridging cultural divides among their families while navigating their careers and romance.

"Beach Rats" Multiple programmers, sales agents and content buyers told TheWrap they're all keen to see this thoroughly modern drama from Eliza Hittman. The movie stars Harris Dickinson as a Brooklyn teen with a grim home life, a budding romance with a female friend and a predilection for meeting up with older men he connects with online.

"A Ghost Story" David Lowery reunites with his "Ain't Them Bodies Saints" stars Rooney Mara and Casey Affleck for a chamber drama about a man who dies, and is forced to watch his loved one grieve over expanses of time.

"The Hero"Sam Elliott stars as an aging country legend confronting his demons (territory that netted Jeff Bridges an Oscar in 2010 for “Crazy Heart”). The film also stars "Orange Is the New Black" star Laura Prepon, which may make it hard for Netflix to resist scooping it up.

"Roxanne, Roxanne" As he keeps chugging along the road to the Academy Awards, "Moonlight" star Mahershala Ali comes to Park City with "Roxanne, Roxanne" -- the story of Lolita "Roxanne Shanté" Gooden, who became a fierce rap battle queen at age 14. Chante Adams stars in this real-life story from writer-director Michael Larnell.

"The Yellow Birds"Alexander Moors ("Blue Caprice") offers up this tale of young Iraq war veterans, which boasts hot up-and-coming stars Alden Ehrenreich (the new Han Solo) and Tye Sheridan. The tale unfolds as a mystery, with a fallen hero's mother (Jennifer Aniston) and a tough-as-nails military official (Jason Patric) searching for answers in a young man's death.

"Step"One of numerous hot docs in Park City, Amanda Lipitz’s opus follows a team of step dancers in Baltimore — an inspiring group of inner-city girls living in the midst of social unrest.

"To the Bone" Marti Noxon, a longtime symbol of female empowerment in TV for her work on "Buffy the Vampire Slayer" and "UnREAL," makes her feature directorial debut with a pitch-black comedy about her own struggle with anorexia. The film stars Lily Collins and Keanu Reeves.

"The Polka King" Jack Black descends on Utah with a meaty role as a Bernie Madoff for the indie music scene. In Maya Forbes’ indie Black plays Polish immigrant Jan Lewan — who became the “King of Pennsylvania Polka” in the 1990s, bribing and cheating investors along the way.

"The Little Hours" Director Jeff Baena continues to surprise, this time with a quiet riot of a film about extremely misbehaving nuns in an Italian hamlet. Reunited with his real-life girlfriend and star Aubrey Plaza ("Life After Beth") and producer Liz Destro, "Little Hours" sees a medieval convent go insane after a sexy day laborer (Dave Franco) moves in.